Juan Pablo Torres-Martínez Department of Economics, PUC-Rio, Brazil.   Rua Marquês de São Vicente 225 Sala 210-F - Gávea Rio de Janeiro, RJ 22453-900 Brazil   jptorres_martinez@econ.puc-rio.br   http://www.econ.puc-rio.br       Primary Research Focus: General Equilibrium   JEL Areas: D5 : General Equilibrium and Disequilibrium: General D4 : Market Structure and Pricing: General